Circuit control apparatus



Dec. 3, 1940. N. J. coNRAD 2,223,601

CIRCUIT CONTROL APPARATUS Original Filed Oct. 15, 1932 Patented Dec. 3, 1940 UNITED STATES CIRCUIT CONTROL APPARATUS Nicholas J. Conrad, Winnetka. lil., assigner to Schweinen- & Conrad. Inc., Chicago. lll., a corporation of Delaware Original application October' 13, 1932, Sell No. 637,593, now Patent No. 2,134,479, ISM 06MB" Divided and this application Septembei' 8, 1938, Serial No. 228,980

12 Claims.

My invention relates, generally, to circuit control apparatus and it has particular relation to circuit interrupters.

The present application is a division of my copending application Serial No. 637,593, filed October 13, 1932, now Patent No. 2,134,470, issued October 25, 1938, and assigned to the assignee of this application.

The invention involves the use of a fusible conductor or link which performs the two-fold function of iirst detecting the presence oi excessive current, reacting accordingly, and second, establishing a gap in which conductivity to current now is destroyed.

The primary object of the invention is to provide a method of and means for increasing the range of interrupting capacity of devices of the foregoing type.

A further object is to secure increased capacity ci' interruption and/or certainty of operation by the use of fusible elements which, by themselves, are of insuilicient capability to accomplish the desired purposes. For example, the capacity or characteristics of a power circuit, or the nature of the overload occurring therein, may be such that a fuse of a design or rating suitable for the circuits of a comparable voltage or rating finds diiiiculty in interrupting the current flow. By the use of my invention certainty of interruption is secured, without change of design or rating of the fuse employed. Hence, with a limited number of standard forms of fuses, automatic circuit interrupters of widely varying ability may be constructed to suit various requirements. e

Another object of my invention is to effect the energization of an auxiliary circuit on operation of a circuit interrupter in a main circuit.

Still another object of my invention is tov operate contact members as a result of the pressure generated on blowing of a fuse device of the blast action arc extinguishing type for connecting an auxiliary circuit for energization w a current source.

According to my invention a main interrupter, which automatically begins the action of mechanically opening the circuit upon the occurrence of overload, is bridged or shunted by a conducting path which is not adapted to carry the rated or normal current ow continuously, as soon as the main interrupter has reached a certain stage where the shunting conductor becomes e'ective.

According to this invention the main circuit interrupter normally carries all of the normal or rated current iiow. The auxiliary circuit interrupter normally carries none of the normal or rated current flow. 'I'hese circuit interrupters are herein illustrated as liquid quenched fuses of a kind and type now on the market, butv the teachings of the present invention are not to be limited to the use of fuses of that kind or type, for the actions and functions which are secured by my invention may be attained through the use of diilerent forms of fuses, as will be apparent from the detailed speciiication appearing hereinafter.

The current flow which is normally carried by the circuit in which the interrupter of my invention appears, passes wholly through the main fuse. Upon the occurrence of overload in the circuit the fusible link of the main fuse melts, and an arc tends to form. The spring then separates the terminals between which the arc exists, and there is injected into the arc an arc extinguishing material the eiect of which is a tendency to deactivate or deionize the gases which constitute the conducting path or substance of the arc. The combined effect of lengthening of the arc and deionization or deactivation of the substance of the arc tends to render the conductive path less conductive to the iiow of current. In other words, the potential drop across the are tends to become greater. As a result of the pressure generated by the evolution of the arc extinguishing gases the auxiliary circuit is completed around the main fuse and a conductive path is established through the auxiliary fuse. This conductive path has sunicient capacity for at least a brief period, to diminish the current flow through the main fuse, whereby the combined action of lengthening the main arc and the deionization of the same results in putting out the main arc and transfer of such current ilow as persists to the shunt or auxiliary circuit. Meanwhile, the separation of the terminals of the main fuse has proceeded to such a point, and the arc extinguishing material has so acted, as to prevent restriking of the arc in the main fuse.

The auxiliary or bridging circuit includes a certain amount of resistance, preferably in the form of a resistance wire such as a nickel chromium alloy, commonly sold on the market as Nichrome or ChromeL Such resistance tends to absorb a part of the potential drop and reduces current flow in this circuit to a value which may be easily interrupted by the auxiliary fuse.

The action is automatic. The separation of the main fuse terminals tends to increase, perhaps not greatly, but very dennitely, the potential drop across the main fuse terminals. The potential across the main fuse terminals is, of course, limited by the I. R. drop through the shunt circuit. This increase in potential drop forces the current through the auxiliary fuse in the shunt circuit. The shunt circuit has a certain thermal capacity which permits the establishmentof a large enough current flow to permit the main fuse to open its .circuit dennitely and. completely. The blowing of the auxiliary fuse takes suilicient time to allow the main arc to be extinguished. Then the progressive action of separating the auxiliary fuse terminals, iniectlng deactivating or deionizing arc extinguishing materials into the arc all cooperate to reduce and ilnally stop the ilow of current in the auxiliary or shunt circuit. While the operations are described as occurring successively, the action as a whole is extremely rapid.

Now, in order to acquaint those skilled in the art with the manner of constructing and oper- -ating a device embodying my invention, I shall describe, in connection with the accompanying drawing, a speciilc embodiment of the same and the actions involved therein.

In the drawing:

Figure 1 is a diagrammatic illustration of an embodiment of my invention in which the pressure of the main fuse switches in the auxiliary fuse: and

Figure 2 is a side elevational viewl partly in section, of one form of fuse which may be employed in the practice of my invention.

Referring first to Figure l, the circuit interrupter is indicated between the conductors i' and 2. Two'liquid quenched fuses Il and I2 are employed, the fuse II being connected through resistors 'l and 8 in parallel with the fuse I2. 'Ihe proportions of the fuses may, for example, be as follows:

Fuse Il, 1,5 ampere rating: fuse i2, 25 ampere rating, with the resistance of theresistors l and l consisting of 55.5 ohms.

Another example of proportioning for a different circuit. is as follows:

Fuse Il, 5 amperes rating; fuse I2, 100 amperes rating; with a resistance. in series, of 55.5 ohms.

The fuses ii and |-2 are preferably well known fuses now on the market. A suitable construction of fuse is shown in Figure 2. Various modincations of the fuse of Figure 2 are disclosed in my Patent No. 2,091,430, issued August 3l, 1937. A suitable fuse for this purpose is also disclosed in my prior Patents No. 1,743,322 of January 14, 1930, and No. 1,834,578 of December l, 1931. A suilicient description of such fuses and their operation is contained in said prior patents. and a brief description of the fuse shown in Figure 2 will sumce for present purposes.

The fuse comprises a glass sleeve l! having metallic terminals at the ends thereof, the lower terminal Il being in the form of a closed cap cemented on the glass sleeve, and the upper terminal I4 being in the form of a ferrule or sleeve likewise cemented on the upper end oi' the glass sleeve 32. 'I'he upper ferrule J4 is closed releasably by a cap which. in case of excessive pressure and upon heavy blowing of the fuse, is adapted to be removed by the internal pressure. The sleeve or ferrule I4 is counterbored to provide a shoulder for mounting the upper terminal plate It, which has slotted spring fingers pressing radially against the walls of the counterbore and -the upper end of which is pressed into or otheraxially against the shoulder formed by the counterbore. A terminal stud fl has a threaded shank extending through the plate $4 and it is held in place by the nut I8 threaded on said shank. A cooperating movable terminal Il is mounted upon a the upper end of the tension spring 4l through the medium of a spring head 4I. to which the spring 40 is anchored. This spring head 42 has a threaded coupling with the terminal I5 and also has a socket 4I to which the nexible cable l0 44 is firmly anchored, electrically and mechanically. The cable 44 shunts the spring 4I. A silver fuse wire 4I formed in the shape of a helix with the ends straightened out axially is connectedy between the movable terminal Il and l the stationary terminal I1. A high tensile strength wire, preferably of nickel-chromium- -alloy composition. indicated at 40, has loops formed at each end and these loops are engaged by pins 41 and 4I in the terminals l1 and Il, respectively. The ends of the fusible link 4l are mechanically anchored in slots in the terminals l1 and Il to give a good mechanical and electrical anchorage, the edges of the slots being riveted or battered over to grip the fuse wire along a considerable length. A liquid director 4l issupported on radially extending arms 5| upon the terminal Il. An explosion chamber is provided about the fusible element by means oi' the sleeve Il,

wise anchored in the barrier plate Il, which barrier plate is threaded into the bore of the ferrule 34 to form a transverse wall. The upper end of the liquid director 40 embraces loosely but fairly closely the upper end of the explosion chamber sleeve I2. The glass sleeve is illled with arc extinguishing liquid to a pointpreferably Just above the liquid director 48.

In operation, upon the occurrence of overload the fuse element 45 first melts. throwing the load over upon the high tensile strength wire 4l, termed the strain wire. Thereupon the strain wire melts and looses the coil spring 40 to retract the terminal 39. \At the same time arc extinguishing liquid is thrown into the explosion chamber 52, this stream of liquid being rapidly vaporized and to some extent broken down, and discharged' upwardly into the chamber formed above the barrier plate 53. Here the vapors and gases are condensed and chilled, and if the arc go is interrupted before the pressure rises to too high a value the operation of interrupting current ilow occurs without blowing of the cap Il.

If the operation is severe, as in a short circuit on a system of large capacity, the pressure in the u fuse may rise to a value high enough to blow oi! the cap IB. I'he terminal plate Il and terminal 31 may then also be expelled, and as the terminal 39 and liquid director 48 descend, vapors and gases of high pressure and very high velocity are so expelled through the explosion chamber, tending to deionize or deactivate the gases carrying the arc. to put out the same.

Referring now to Figure l, it will be observed that the cap l5 is omitted from the fuse l! and that instead it is provided with an expansible member or bellows 19, which carries a contact III adapted to cooperate with the contact I2, forming the terminals of the gap In this case the pressure developed in the fuse I2 switches in the 'l0 shunt circuit by either bringing the contacts Il and 82 into engagement or bringing them near enoughy to each other that the voltage drop across the gap will break the gap down and switch in the shunt circuit.

In operation the fuse I2 normally carries the entire current flowing through the circuit represented by the conductors I and 2. On the occurrence of an overload in this circuit, the fuse I2 operates as previously described. The pressure generated as a result of the blast action of the arc extinguishing material causes the expansible member or bellows 19 to be extended for closing the gap 55. In such case the contact 80 may be moved into contact engagement with the contact 82. In either case the auxiliary circuit is then -connected for energization to the current source represented by the conductors I and 2. The current ilow is then transferred to the fuse II but it is materially limited by the resistors 1 and 8. The fuse II then operates in the manner previously described to open the path through the auxiliary circuit in which it is connected. Since X the path between the conductors I and 2 has now been opened by the fuse I2 in the main circuit and the fuse Il in the auxiliary circuit, no further flow of current takes place.

I do not intend to be limitedto the specific details which I have above described. Ido not 4wish to limit the arc extinguishing material, nor

the specific form of the fuses, to the forms above described for the reason that those skilled in the art will at once appreciate that the mode of operation which I have explained may be embodied in forms structurally quite different but mechanically the equivalent of the aforesaid.

I claim:

1. A circuit control device comprising, in combination, a circuit interrupter of the blast action arc extinguishing type for connection in a power circuit, an auxiliary circuit including a resistor normally out of said power circuit, and contact means arranged and adapted to connect .said auxiliary circuit in said power circuit in shunt circuit relation to said circuit interrupter, said contact means being operated by the blast occurring on operation of said circuit interrupter.

2. A circuit control device comprising, in corn-A bination, a circuit interrupter of the blast action arc extinguishing type for interconnecting a pair of circuit terminals, a member operatively connected to said circuit interrupter and disposed to be moved on the occurrence of a blast initiated by operation of said circuit interrupter, contact means operated by said member, and an auxiliary circuit including a resistor normally out of the circuit between said circuit terminals and arranged and adapted to be connected in shunt circuit relation to said circuit interrupter on operation oi said contact means.

3. A current interrupter comprising, in combination, a fuse device for connection in a power circuit, an auxiliary circuit including a resistor normally out of said power circuit, and contact means arranged and adapted to connect said auxiliary circuit in said power circuit in shunt circuit relation to said fuse device, said contact means being operated as a result of the blowing of the fusible element of said fuse device.

4. A current interrupter comprising, in combination, a fuse device for interconnecting a pair of circuit terminals, a readily deformable member operatively connected to said fusedevice and disposed to be deformed on the blowing of the fusible element of said fuse device, contact means operated by said deformable member, and an auxiliary circuit normally out of the circuit between said circuit terminals and arranged and adapted to be connected in shunt circuit relation cuit terminals and including a fuse device arl ranged and adapted to be connected in shunt circuit relation to said rst mentioned fuse device on operation of said contact means.

6. A current interrupter comprising, in combination, a fuse device of the blast type for interconnecting a pair of circuit terminals, a member operatively connected to said fuse device and disposed to be moved on the occurrence of a blast initiated by operation o! said fuse device, contact means operated by said member, and an auxiliary circuit normally out oi the circuit between said circuit terminals and including a resistor arranged and adapted to be connected in shunt circuit relation to said fuse device on operation of said contact means.

7. Circuit control apparatus comprising, in combination, a. circuit interrupter of the blast action arc extinguishing type for connection in an electric circuit, an auxiliary circuit, and contact means arranged and adapted to connect said auxiliary circuit in shunt circuit relation with said circuit lnterrupter, said contact means being operated by the pressure generated by the blast occurring on operation of said circuit interrupter.

8. Circuit control apparatus comprising, in combination, a circuit interruptor of the blast action arc extinguishing type, readily deformable means operatively connected to said circuit interrupter and disposed to be deformed by the pressure created by the blast resulting from operation thereof, contact means operated by said deformable means, and an auxiliary circuit larranged to be connected in shunt circuit relation with said circuit interrupter on operation of said contact means.

9. Circuit control apparatus comprising, in combination, a fuse device of the blast type, readily deformable means operatively connected to said fuse device and adapted to be deformed by the pressure generated by the blast resulting from operation thereof, an auxiliary circuit, and contact means operable as a result of deformation of said deformable means for connecting said auxiliary circuit in shunt circuit relation with said fuse device.

10. Circuit control apparatus comprising, in combination, a fuse device of the blast type, an expansible bellows operatively connected to said fuse device and adapted to be expanded by the pressure generated by the blast resulting from operation thereof, an auxiliary circuit, and contact means operable by expansion of said bellows for connecting said auxiliary circuit in shunt circuit relation with said fuse device.l

11. Circuit control apparatus comprising, in

combination, a liquid fuse device adapted to be mounted in an upright position for connection in a circuit to automatically interrupt the same on the occurrence of a predetermined overload, a ilexible bellows hermetically sealed to one end of said fuse device and forming therewith a unitary device, said ilexible bellows itself serving to close said one end of said fuse device and expanding as a result of the pressure generated thereby on lows closing one end o! said fuse device and located directly in the path of the blast generated on blowing of said fuse device and adapted to expand as a result of the pressure of said blast,

and means operated by said fiexible bellows on 5 expansion thereof.

menons J. CONRAD. 

